Wanting to Process Steps in Right Order...

My primary reason for using jb on my iPhone 3G is to unlock it. With that in mind, and after all the reading I've done on this forum, it looks like the best plan is to jb using PwnageTool.

My question though is regarding the process. I'm doing the jb to unlock my phone but noticed that one of the questions I need to answer during the jb is whether I need hactivation (whether my phone is unlocked yet or not...) kind of confused about how it could it be unlocked prior to the jb?

Specifically, it's not yet but that would be my next step. I have a "valid" SIM in the phone at the moment and then will hopefully replace that SIM with another from another US carrier this afternoon.